use strict ;
use warnings ;
my @stopwords = qw{ sous } ;
my $string = "sous sous-alimentation" ;
my ($rx) = map qr/(?:$_)/, join "|", map qr/\b\Q$_\E\b(?!\-)/, @stopwords;
$string =~ s/$rx//g ;
print $string ;
__END__
 sous-alimentation